Local gun buyback programs have increased in cities across the country in the wake of the Sandy Hook Elementary School massacre in Connecticut that took the lives of 20 children and six adults in December. And the national debate continues, as President Obama awaits this week’s recommendations from Vice President Joe Biden and members of Congress on gun legislation.

But researchers who have evaluated gun control strategies say buybacks – despite their popularity – are among the least effective means of reducing gun violence. They say targeted police patrols, intervention efforts with known criminals and — to a lesser extent — tougher gun laws all work better than buybacks.

“They make for good photo images,” Michael Scott, director of the Center for Problem Oriented Policing, based at the University of Wisconsin’s law school, told The Associated Press. “But gun buyback programs recover such a small percentage of guns that it’s not likely to make much impact.”

Government estimates show more than 310 million guns in America today – almost enough to arm every person in the entire country.

The relatively small number of guns recovered isn’t the only problem, Scott told the AP. Buyback programs tend to attract people who are least likely to commit crimes and to retrieve guns that are least likely to be used in crimes.

Scott and other researchers stated that violent criminals – the people who do most of the shooting and killing – steer clear of buyback programs unless they’re trying to make some quick cash by selling a weapon they don’t want anymore. Weapons dropped off at buyback campaigns are often just hunting rifles or old revolvers from a person’s attic.

“They don’t get a lot of crime guns off the street,” Matt Makarios, a criminal justice professor who studied buyback programs while at the University of Cincinnati in 2008, told the AP. “You’re only going to reduce the likelihood of gun crimes if you reduce the number of guns used in crimes.”

However, some successful buybacks have occurred in certain cities.

A December gun buyback program in Los Angeles took 2,000 weapons off the streets – including two rocket propelled grenade launchers. The program had a “no questions asked” policy that encouraged residents to voluntarily drop off firearms in exchange for grocery store gift cards.

“Those are weapons of war, weapons of death,” LAPD Chief Charlie Beck told the Los Angeles Times. “These are not hunting guns. These are not target guns. These are made to put high-velocity, extremely deadly, long-range rounds down-range as quickly as possible, and they have no place in our great city.”